Systems can be used to cut or mark a workpiece that has a thickness and is composed of a type of material such as steel, metal, aluminum, among others. Generally, a cutting operation is cutting completely through the workpiece and a marking operation is marking a surface of the workpiece. Such systems can include, laser cutting systems, waterjet cutting systems, automated cutting systems, plasma cutting systems, among others.
Laser cutting systems uses a laser to cut materials. A laser cutting system directing a laser at the workpiece to be cut or marked. The workpiece can be either melt, burned, vaporized away, or is blown away by a jet of gas, leaving a high-quality surface and clean edge. For instance, laser cutting systems can be used to cut or mark flat-sheet material as well as structural and piping materials.
Waterjet cutting systems uses high-pressure jet of water, or a mixture of water and an abrasive substance to cut or mark a workpiece. Waterjet cutting systems can cut or mark materials such as metal or granite (using a mixture of water and an abrasive substance) and rubber or wood (using water without an abrasive substance).
Plasma cutting tools used to cut or otherwise operate on a workpiece typically comprise a gas nozzle with an electrode therein. Generally, plasma tools direct gas through a nozzle toward the workpiece, with some or all the gas ionized in a plasma arc between the electrode and the workpiece. The arc is used to cut, mark or otherwise operate on the workpiece.
In most tools, a pilot arc is first established between the electrode and the nozzle. Then, the pilot arc is transferred from the nozzle to the workpiece for cutting and/or other operations. For example, some tools use contact-based starting, with the electrode and nozzle initially in contact with one another. While current is passing through the electrode and nozzle, the electrode and nozzle are moved apart to create a gap. A spark across the gap initiates the pilot arc in a successful starting operation.
Other tools use non-contact starting, which can advantageously avoid wear on the electrode that is aggravated by contact during starting and can also avoid the need to have more complexity in terms of additional moving parts to bring the nozzle and electrode into and out of contact. To initiate a plasma arc in a non-contact start, a high electric potential must be generated between the spaced apart nozzle (which acts as the anode) and the electrode (which acts as the cathode). The generated voltage must exceed the break over voltage associated with the air gap between the nozzle and electrode. The break over voltage can be influenced by factors such as distance between nozzle and electrode, type of gas present, velocity of gas flow, and nozzle and electrode geometry.
Cutting and/or marking systems can include a number of adjustments a user can adjust and what is needed is an improved technique to prevent adjustment that is detrimental to a cutting or marking operation.